Something is wrong, I haven’t seen any name calling yet. Everyone must be mellowed out because of the holiday weekend.
[QUOTE=+A465B;133098]The ship passed chain, we made it up on deck to our towline, let out abt 3000 ft of 12 inch nylon and towed like hell.[/QUOTE]
now tell me how many tugs or any other type vessels would have 3000’ of 12" (4" dia) nylon hawser available to use? Maybe a Navy T-ATF or T-ARS but what commercial?
Everyone is still staggered from the Best Posts diatribe rehash. Man, that guy had some waaaay serious anger issues.
[QUOTE=c.captain;133107]now tell me how many tugs or any other type vessels would have 3000’ of 12" (4" dia) nylon hawser available to use? Maybe a Navy T-ATF or T-ARS but what commercial?[/QUOTE]
Commercial ? 3000 ft? Probably none. The tow was an SL7 prepo ship.
Everything I ever did commercial was on chain bridles with wire towline.
But I’ll tell you, if you can tow safely on nylon it is one smooth ride.
[QUOTE=tugsailor;133048]Alternatively, if towing on bridle with a leg to each side of the bow the ship might settle down off to one side by shortening, or lengthening, one leg of the bridle. [/QUOTE]
I suppose it would be possible to stop off both anchors and pass both chains down to the tug. Presumably the tug crew could rig a bridle. For that matter you could rig a bride and a pig tail with the ship’s chain. Plenty of anchor chain on board in any case. Be a matter of figuring out the easiest way to get it where you wanted it.
It goes without saying that what you could do would depend on the on-scene weather.
I think the wx was 30’ seas and 20min to make tow, sounds like you would have to shoot from the hip on this one.
It takes more than 20 minutes to make up an ocean tow alongside the dock.
[QUOTE=rshrew;133154]I think the wx was 30’ seas and 20min to make tow, sounds like you would have to shoot from the hip on this one.[/QUOTE]
I read the OP that the tow would have to withstand 30 ft seas , not that you would hook up in 30 ft.
[QUOTE=Kennebec Captain;133161]I read the OP that the tow would have to withstand 30 ft seas , not that you would hook up in 30 ft.[/QUOTE]
'Zactly.
Use the chain … and lots of it. Doesn’t hurt a thing.
Now someone tell us about towing on Spectra. Why would one do it?
[QUOTE=+A465B;133163]'Zactly.
Use the chain … and lots of it. Doesn’t hurt a thing.
Now someone tell us about towing on Spectra. Why would one do it?[/QUOTE]
I have never towed on spectra. But spectra might be the way to go ( because it is light and strong) if a tug had to get a line up on a dead ship that had been abandoned.
[QUOTE=tugsailor;133160]It takes more than 20 minutes to make up an ocean tow alongside the dock.[/QUOTE]
In good weather you could get a line up and start towing in 20 minutes, just like a ship assist job. Once you had it in tow you run heavier gear and upgrade your tow.
:That might not be what the OP had in mind.
[QUOTE=Kennebec Captain;133165]In good weather you could get a line up and start towing in 20 minutes, just like a ship assist job. Once you had it in tow you run heavier gear and upgrade your tow.
:That might not be what the OP had in mind.[/QUOTE]
Sure you can go alongside, let the ship drop a heaving line, and put up a small soft line and tow on it in good weather in less than 20 minutes. And that’s probably what I would prefer to do while spending a couple more hours in good weather rigging up heavy gear for a 1000 mile ocean tow with 30 foot seas expected.
If the ship could drop two shots of chain, and I could pre-rig the Orville hook enroute, and if I were to get lucky and catch the chain on the first try the I might get the ship in 20 minutes. Or it might take all day . But I wouldn’t want to tow the ship very far on the Orville hook before rigging permanent gear.
Spectra is great to tow with. Like cable there is no shock absorption but for its strength it’s much easier on the deck crews. I have used bridles that are 50/50 nylon/spectra and those work great too. The only problem w/ spectra is that running through a level wind and onto a drum in/out will chafe it up and shorten its life a bit and for the cost it’s cheaper to use cable for the kind of towing I generally do.
This thread just keeps getting better. Lots of experience on this forum.
Answers to some of your questions / statements:
[B]Injunear[/B] The ships crew would ride the ship to the the destination. If the rudders and bow thruster are active, we certainly ask for help. In this scenario both are down. Yes 950 ft with 35 ft draft and 8000hp is certainly a handful. Knowing the limitations on what is actually possible and what is downright dangerous is the captains job.
[B]Kennebec[/B] There usually isn’t a salvage crew unless its a real emergency situation such as a collision, fire, or grounding. Otherwise its just regular tug crew. If we were to use the ships anchor chain, your method is pretty much spot on. Although we probably wouldn’t need such a long and large diameter messenger for the chain. We could suck it up with the capstan, then put the chain in the shark jaws to safely make the connection. We probably wouldn’t want to use both anchor chains in the event the connection breaks and the ship needs to drop the hook quickly to avoid grounding, collision, etc…
[B]Topsail[/B] Excluding the really heavy seas, that picture is about exactly the scenario I’m envisioning. Approximately a 200’ AHTS hooking up to a large ship offshore. I think there was some confusion about the weather in my scenario. I meant the tow needed to handle 30’ seas… Not make the connection in 30’ seas. I can see some of the tow gear in the picture, but have a hard time deciphering the connection sequence. Crazy picture by the way…
[B]+A465B[/B] Don’t think our company would go for the 3,000ft of 4" nylon, but I’m sure its a nice ride:) Your question about Spectra… That’s something we need to discuss. Has anyone on this thread towed long distances in heavy seas with spectra going through the bullnose or a spectra bridle? Samson makes some tough chaffing gear, but would it hold up in this scenario?
In summary, here’s a list several possible tow connections. We all know bridles are better, but for this scenario we are using a single part.
[B]1.[/B] 70’ x 2.25" Wire pennant to the ship --> 300’ of 9" circ Spectra --> Shot of 3" chain --> Tow wire
[B]2.[/B] 120’ x 2.25" Wire pennant to the ship --> Shot of 3" chain --> Tow wire
[B]3.[/B] 350’ x 9" circ Spectra to the ship with heavy duty chaffing gear --> Shot of 3" chain --> Tow wire
[B]4.[/B] Shot of 3" chain to the ship --> Tow wire
[B]5.[/B] Anchor chain paid out through the bull nose --> 3" chain --> Tow wire
Excluding the anchor chain, the ships crew would have to stopper off the gear, run it around the fwd bitt, then secure it to a side bitt to spread the load. 3" Chain being the most difficult but safest for chaffing… Spectra being the easiest but most susceptible to chaffing.
Ideas to prevent the tow from yawing
- Drop a large sea anchor off an outboard stern of the tow such as a string of Yokahamas
- Shorten one bridle leg if using a bridle
- Trim the ships stern down
- If towing on a single part, break tow gear and set up a bridle
- Use the ships rudder or bow thruster (Not applicable for this scenario)
Whether or not to tow over the rails out of the pins? [I]Different opinions on this one[/I]
I must say that I didn’t expect this thread to take off and get such great feedback. As a Mate aspiring to move up to Captain, I look up to your experience and knowledge. I can’t thank you enough for sharing your experiences. This thread shows that emergency towing isn’t black and white and there are many different ways to approach the connections and tow procedures.
Bests,
Deviated
Deviated,
You got answers because thinking is more fun than just taking the piss out of someone.
Excepting having a go at the Anchorage Commodore.
PS - Didn’t mean to suggest use nylon … it is just what we had at the time and that captain preferred to use it. Most of the time we towed on wire.
[QUOTE=Deviated;133183]
[B]Kennebec[/B] There usually isn’t a salvage crew unless its a real emergency situation such as a collision, fire, or grounding. Otherwise its just regular tug crew. If we were to use the ships anchor chain, your method is pretty much spot on. Although we probably wouldn’t need such a long and large diameter messenger for the chain. We could suck it up with the capstan, then put the chain in the shark jaws to safely make the connection. We probably wouldn’t want to use both anchor chains in the event the connection breaks and the ship needs to drop the hook quickly to avoid grounding, collision, etc…
[/QUOTE]
In my example I was assuming I was passing the anchor chain to the tug using ship’s gear, the size lines is what I have aboard.
Basically the ship has a anchor chain and the tug has a tow wire, you need to get them connected at sea.
You could either pass the chain to the tug or get a tow line up to the deck of the ship. In good weather likely the first because that is what tug crews do, in bad weather the second because of the weight of the gear. Three inch anchor chain weighs 4 tons to the shot (90 feet).
In either case if you start with a heaving line or the line from a line-throwing gun (like parachute cord), next the SOLAS required messenger. Next you likely would pass a line heavy enough that will not part when we try to lift the gear (either the anchor chain to the tug or tow line to the ship) and long enough that we will not run out if the vessels drift apart during the operation.
Having the messengers too long is just a minor nuisance compared to the problem of having them too short. If they are too short you will lose your connection (line be let go or will part) if the vessels drift apart during the operation. Ideally you want the receiving crew to just have enough aboard (in hand for light stuff, to power for heavy) before the sending crew sends the next size up. In practice you have to use what you’ve got.
If you don’t have adverse weather conditions, you will be short of time … Murphy’s Law. I am questioning myself about the state of ships readiness to be towed in emergency. I sailed on many types of vessels and even on VLCC’s or ULCC’s, I cannot recall any single emergency towing drill. I towed many dead bulkers for their last voyage to the scrap yard. From my experience, a unique tow line through the bull nose (center lead) is working very badly. The towed vessel is yawing all the time and is very difficult to lead even after trying all kinds of scope lengths. The best arrangement was welded Smith Clamps on the main deck, bridle anchor chains arrangement via openings made through either side of the bow (cheek) plating, fish plate, nylon tow line and finally steel tow line. We had to keep both anchors and pilot ladders on each side ready in case of emergency. Etc.
But in case of emergency, it is a totally different matter. I think that vessels should be equipped with some kind of DYNAMICA Bridle Ropes ready to be used. This type of rope is even stronger than steel rope. It has a very low elongation, UV stable, resistant to chemical, abrasion resistant and most important, very light and easy to handle. A DYNAMICA rope of 1¼ inch diameter has a breaking stress at the splice of 70 metric tonnes and weight 95 pounds per 300 feet of length. It would take minutes to install and easily… thrown to the tractor tug to be then fasten to the Fish Plate.
If you ever succeed to use the misfortune vessel own anchor chains as bridle but then the tow line parts, you could find yourself checkmated, game over. Never go aground with the anchors in the pipe, they say. You don’t have to take extraordinary measures nor being a hero.
http://www.secondair.com.au/dynamicarope/drange.htm#properties
[QUOTE=Topsail;133198]
If you ever succeed to use the misfortune vessel own anchor chains as bridle but then the tow line parts, you could find yourself checkmated, game over. Never go aground with the anchors in the pipe, they say. You don’t have to take extraordinary measures nor being a hero.
[/QUOTE]
I never recommended using both chains, I just said I supposed it could be done. Mariners make risk based trade-offs decisions all the time, this would be no different. If circumstances were such that it was judged the the risk was too great or the risk could not be mitigated, it obviously shouldn’t be done. On the other hand if it was judged that the a bridle lowered the risk of losing the tow sufficiently to mitigate using the other chain then it should be considered. Obviously, weather, time constraints and other circumstances would have to be considered.
As far as your non-negotiable rule of never going aground with the anchors in the pipes, breaking a chain at the detatchabale link is not an irrevocable act. You could build your bridle and reattach both anchors if you felt it was necessary. Anyway I would think a ship with two anchors in the hawepipes and 18 shots of chain aboard is far from checkmated.
K.C. You are a very valiant and brave Master. But playing around with the anchor chain of a vessel the size of the SHINYO SAWAKO, is to my humble advice a very difficult task. I worked on a vessel that size and only one (1) chain link weight like 250 pounds ! Can you imagine pulling around any length of that sort of chain in adverse weather conditions. I agree that on much smaller vessels, it worth a very well coordinated try.
Again, a DYNAMICA rope of 1¼ inch diameter has a breaking stress at the splice of 70 metric tonnes and weight 95 pounds per 300 feet of length, whereas a rope of 2½ inch diameter has a breaking stress at the splice of 225 metric tonnes and weight 370 pounds per 300 feet of length. I think it is cheaper to supply a vessel with some kind of ready to use DYNAMICA Bridle Ropes than losing the vessel on the rocks, like it is cheaper to use a tug to dock than welding frames and plates to fix a huge hole in the hull. Not to mention risk of oil pollution. But I’m not convince that office white collars would agree. But if they receive a formal demand in that sense, they will be stuck with it ! CYA is the very fine word.
Do you means dyneema? If so its fun to play with and have used it as a bridle successfully.
A good customer will have dyneema/spectra tow gear ready to go shoreside a helicopter ride Away.